NASA says, ‘A broad and substantial coronal hole (the much darker area across the top of the Sun) faced directly towards Earth for several days (Oct. 9-12, 2015).

‘Coronal holes are magnetically open areas that are one source of high-speed solar wind. They appear dark when viewed in many wavelengths of extreme ultraviolet light, such as seen here. At times, the solar wind can generate aurora at higher latitudes on Earth.’